What does "enneagon" mean?

A polygon with nine sides; a nonagon.

What is a synonym for "enneagon"?

Common synonyms include: nonagon.

Pronounced //ˈɛ.niː.ə.ɡən//.

/ˈɛ.niː.ə.ɡən/ noun

noun ·Rare ·Advanced level

Noun

"A nonagon, sometimes called an enneagon, is a polygon with nine sides."

From ennea- + -gon.